1. Field of the Invention
This invention relates to an airfoil anti-icing assembly, method and system. More particularly, the assembly, method and system of this invention use hot gases which are directed into the interior cavity of the airfoil and caused to swirl, thereby effecting sufficient heat transfer to avoid icing of the exterior surface of airfoils such as aircraft wings and slats. The hot gases are directed into the airfoil interior cavity without using tubes or spray ducts.
2. Background Information
The use of aircraft jet engine exhaust gases or bleed air in aircraft anti-icing systems to prevent the formation of ice on aircraft wings, engine inlets, etc. is well known to those skilled in the art. For example, co-assigned U.S. Pat. Nos. 4,688,745 and Re. 36,215 disclose a jet engine anti-icing system for preventing jet engine icing, in which hot gas, such as air, is obtained from the jet engine and directed to an annular housing located around the leading edge of the engine housing. Typically, one or more tubes are employed to direct the hot gas flow within the annular duct, as depicted, for example, in FIGS. 3-7 of U.S. Pat. Nos. 4,688,745 and Re. 36,215. The tube or tubes are positioned to discharge hot gases in a direction tangent to the center line of the annular housing, thereby causing the hot gases to entrain air within the housing and swirl within the housing interior. This entrainment and swirl enables the heat transfer to be sufficient to prevent the formation of ice on the housing exterior.
U.S. Pat. Nos. 5,873,544 and 6,003,814 disclose anti-icing conduit systems for the moveable wing slat of an aircraft wing. More particularly, hot compressed bleed air is conducted from the aircraft engine to the interior portion of the moveable wing slat via a conduit system. As shown FIG. 1 of each of U.S. Pat. Nos. 5,873,544 and 6,003,814, the bleed air is introduced into the interior portion of the moveable wing slat via a spray duct or tube having openings therein. The spray duct is supported by an interior wall of the moveable wing slat.
However, the use of such tubes or spray ducts as discussed above to introduce heated gases into the annular regions of jet engines and wings has several disadvantages. First, such tubes and spray ducts require additional materials, and thereby results in attendant additional labor and material costs for the manufacture of systems employing such components. Moreover, as depicted in FIGS. 3-7 of U.S. Pat. Nos. 4,688,745 and Re. 36,215, and FIG. 1 of each of U.S. Pat. Nos. 5,873,544 and 6,003, 814, a duct wall of the engine or slat annular region must support the tubes or spray ducts to maintain them in proper position within the duct, thereby adding additional load to the duct wall.
In view of the foregoing, it would be useful to have an assembly, method and system for preventing icing in airfoils such as aircraft slats and wings which avoided the use of tubes or spray ducts to provide heated gases to the corresponding conduit or duct portions of the airfoil. It is one object of this invention to provide an assembly for anti-icing systems for airfoils which does not employ such tubes or spray ducts. It is one feature of the assembly of this invention that hot gases such as engine bleed air are introduced into a conduit or duct portion of an airfoil such as an aircraft slat or wing without using tubes or spray ducts. Instead, the hot gases are introduced via a simple inlet conduit. The assembly of this invention achieves the necessary swirl of the hot gases required for effective heat transfer yet, advantageously avoids the additional materials required for such tubes or spray ducts, as well as the attendant additional labor and material costs associated therewith.
It is another object of this invention to provide a method for preventing icing of airfoils which employs the assembly of this invention. It is another object of this invention to provide an anti-icing system for airfoils which employ the assembly of this invention. Additional objects, features and advantages of this invention will be apparent to those skilled in the art from the detailed description of the invention set forth herewith.
The airfoil anti-icing assembly of this invention comprises:
(a) an airfoil having an exterior surface and interior wall defining an interior cavity, and bottom, middle and side portions all adjacent to the interior cavity;
(b) an inlet plenum integral to the airfoil, wherein the inlet plenum comprises (i) an inlet baffle capable of directing hot gases into the airfoil interior cavity and (ii) a throat section interfacing the inlet plenum and airfoil interior cavity; and
(c) an outlet plenum integral to the airfoil, wherein the outlet plenum comprises an outlet baffle capable of directing hot gases from the airfoil interior cavity.
The airfoil anti-icing method of this invention comprises providing hot gases such as jet engine bleed air to the airfoil assembly of this invention, swirling the hot gases within the airfoil interior cavity, and discharging the hot gases from the airfoil interior cavity through the airfoil outlet end. The system of this invention comprises a source of hot gases, typically jet engine bleed air, and the airfoil assembly of this invention.